Typewriting machine



Aug. 9, 1938. w. F, HELMOND 2,126,326

TYPEWRITING MACHINE Original Filed Nov. 1, 1935 2 Sheets-Sheet l Aug. 9., 1938. w. F. HELMOND M TYPEWRITING MACHINE ori inal Filed Nov. 1, 1935 2 Sheets-Sheet 2 m N R ,m A

Patented Aug. 9, 1938 UNITED STAT T iE'i" OFFICE TYPEWEKTHNG MACHINE Original application November 1, 1935, Serial No.

47,731. Divided and this application October 8, 1937, Serial No. 167,906

6 Claims.

This invention relates to sound-deadening devices for typewriting machines and other utensils having sheet-steel or other weldable workedmetal parts.

Primarily the intensity of the sound depends upon the amplitude of the vibrations, and the prolongation or repetition of sound by reflection or reverberation is resonance. The impact of the type-bars upon the platen of a typewriter sets up vibrations and resonance proportional to the form and structure of the several essential parts of the machine. ularly that of sheet-metal parts is therefore effective to deaden the sonorousness of these parts.

An object of the present invention is to improve the construction of the sonorous parts, and more especially of the sheet-metal parts in a typewriter, so as to reduce vibration to a minimum, more especially so to improve the construction of the mask in a portable typewriting machine, so to improve the construction of the paper-table in a typewriter, so to improve the construction of the stop-ring for type-bars, so to improve the construction of the platen, so to improve the construction of panel plates, and so to improve the construction of other parts, devices or elements, directly or indirectly connected with any typewriter, it being obvious that the reduction of sound and the elimination of sonorousness are important utilities in this art.

Another object of the invention is to eliminate the sonorousness of sheet-metal parts in any utensil utilizing steel or other weldable worked metal, preferably sheet-steel, and more particularly where, during the operation of such utensils, there is a tendency to set up vibrations.

Other objects will appear as the description proceeds.

To deaden or muffle the sound of a typewriter, sheet-metal parts have been lined internally with linoleum, felt, rubber, asbestos, cork, and sometimes with intermediate layers of lead. In any or all of these constructions, it is obvious that the wall formed by the sheet-metal and its sounddeadening lining is many times thicker than is the sheet-metal alone, and also that the lining or interlining adds nothing to the strength of the sheet-metal wall.

A feature of the present invention is to lock 50 together two similar pieces of sheet-metal, but of plies of less than the usual thickness of each, surface upon surface throughout, positively by the use of spot-welding, whereby vibrations in either piece are immediately deadened or choked by those in the other piece. Experimentation has To choke the vibrations, particrevealed that for a complete and satisfactory deadening effect the surfaces of the contiguous sheets of metal must be positively locked by spotwelding, so that at definite places the contiguous pieces of sheet-metal are integrated one with the other, particularly at the loci of the maximum amplitude of vibration of said pieces. Important consideration attaches to the construction of spot-welding similar pieces having fractions of the usual thickness, so that the resulting nonvibrating or sound-deadening unit is identical in size or thickness with the part or piece for which it is substituted, thereby effecting a great saving in cost in introducing this improved sound-deadening construction throughout a typewriter, or in any other utensil made of weldable worked metal, the sound of operation being decreased proportionally more in each instance when and as this improved sound-deadening device is used in additional places in the typewriter or utensil.

In spot-welding one piece of sheet-metal or other weldable worked metal upon another piece of sheet-steel, in order to substantially eliminate the sound, it is important that the sonorousness of one plate be approximately the same as that of the other. Plates of the same composition, size, form and thickness are substantially the same in sonorousness. Variation in the relationships in any of these elements varies the sonorousness. A convenient form of plate is one of the same size, form, thickness and material as the other plate, so that when the two plates of steel or other weldable worked metal are spotwelded together, the sonorousness of the plates is substantially identical so that when integrated that this invention is applicable to typewriters or other metal utensils having frames of steel or other weldable Worked metal, preferably sheetsteel.

By spot-welding along axial or medial lines of the adjacent contiguous small-area pieces of sheet-metal a good result is obtained with a minimum of the spot-welding operations. In such pieces that have a relatively small-area spot- Welding along an axial or medial line effectively integrates the contacting pieces at or in the zones of maximum potential amplitude of vibration, and so therefore more effectively binds the surrounding surfaces one upon the other in direct proportion to the increased tendency of the pieces to vibrate caused by blows or impacts in any part means of spot-welding.

of the typewriter, or other utensil, comprising metal elements in combination with one another. In other words, the spot-welding at the axial or medial lines integrates the two pieces at or in the central zone of these pieces and so positively and completely chokes off all vibration or motion of the two pieces relatively to one another in the surrounding area, thereby completely choking or deadening the sonorousness of either of the integrated pieces of sheet-metal. Or again to express it popularly, by increasing the trouble of sonorousness by splitting the sheets of metal, the trouble of one sheet is killed by the trouble of the other by integrating the contiguous sheets by When, however, the sheets are cut to form extensions, spot-welding substantially centrally of the extensions is desirable for good results in choking the sonorousness, and when surfaces are in a different plane from other parts of the sheets, spot-welding substantially centrally in the different plane surfaces is desirable for the effective elimination of sonorousness.

This application is a division of my application, Serial No. 47,731, filed November 1, 1935, Patent No. 2,104,482, Jan. 4, 1938.

Other features and advantages will hereinafter appear.

In the accompanying drawings,

Figure 1 is a perspective view of a mask for a portable typewriter, with parts cut away in a side and rear wall to show the improved sounddeadening construction.

Figure 2 is a perspective View of the front cover of a portable typewriter.

Figure 3 is a side elevation of a portable machine, with some parts removed and other parts shown in section where they embody the improved sound-deadening construction.

Figure 4 is an isometric view of a paper-table of the sonorousness-deadening construction.

Figure 5 is an isometric view with parts of the top cover, and the front cover broken away to show the embodiment of the invention in an Underwood noiseless typewriter.

igure 6 is a side elevation, partly in section, showing a type-bar in engagement with the cushioned stop-ring embodying the improved sound-deadening construction.

Figure '7 is a front View of the stop-ring,

Figure 8 is a cross-section of the platen with a juxtaposed type-bar head, showing the improved sound-deadening construction both faced and backed by rubber.

Figure 9 shows an edge view or section of a snot-welded noiseless plate.

Figure 10 is a plan view of the platen shown in Figure 8, but with a part broken away, and showing a lengthwise section.

Figure 11 is a view similar to Figure 10, but

Y. with the outer rubber platen-surface stripped Figure 12 is an isometric inside view of the s de frame of an Underwood standard typewriter, showing a panel for closing the opening in the side frame, parts of the frame and the panel being broken away.

In Figure 1, a sheet-metal mask II of an Underwood portable typewriter, as shown in patent to Lentz No. 1,901,398, of March 14, 1933, is formed of an inner ply l2 and an outer ply l3, the plies being sheet-metal, of steel or other weldable worked metal, and having identical form, size, material and thickness, and being spot-welded together at a plurality of loci I l.

An inwardly-turned flange I5 forms the top edge, and at the bottom edge on either side are apertured integral inreaching lugs I6. The loci of the spot-welding I4 are in substantially central or medial zones of each flat plate, except in the upward side extensions, where additional spotwelding is placed substantially centrally or medially in the area of the upward side extensions. The loci of the spot-welding I4 are determined by the loci of the maximum potential amplitude of vibration in the plies, and in metal sheets of identical form, size, material and thickness, such loci are usually in central or medial zones. In sheets of narrow width, by so locating the spotwelding, a single row of fewer spots suilices completely to deaden the vibrations and eliminate the sonorousness, but where there are protuberances in edges of the sheets the location of spotwelding in the protuberances centrally or medially thereof effectively chokes or nullifies the vibrations and so eliminates the sonorousness thereof.

In Figure 2, a sheet-metal front cover I! of an Underwood portable typewriter is formed of an inner ply i2 and an outer ply I3, the plies being sheet-metal, of steel or other weldable worked metal, and being spot-welded together at the loci I4. It will be noted that the top surfaces of the front cover I! lie in a plane or planes substantially at right angles to the plane formed by the front face of the cover, so that separate spot-welding is made in the central or medial zones of these top surfaces, inasmuch as such zones possess the maximum potential amplitude of vibration with consonant sonorousness.

In Figure 3, the mask II and the front cover H are assembled with a frame I8 of an Underwood portable typewriter, as shown in patent to Lentz, No. 1,901,398, mounted on legs I9, the former by means of inwardly-turned lugs on the frame of the machine, which lugs are tapped to receive screws 2i passed through apertures in the lugs I6, and the latter by the inwardlyturned lugs 28 tapped to receive the screws 2| passed through apertures in the front cover, and the rear wall of the mask II is also secured to the rear wall .53 of the frame I8 by the screws 2|. A carriage 22 reciprocates with reference to the frame I8 by means of the rear carriage-rail 23 and the rear frame-rail 24 and interposed anti-friction elements or balls 25 and the front carriage-rail 26 and the front frame-rail 21 and interposed balls 25, and has the usual roll platen 28 carried thereon across the path of movement of type-bars 29. A paper table 30 embodying the sonorousness-choking invention is mounted on the carriage by means of apertured pendent lugs 3| pintled upon supports 32. Reference to Figure 4 clearly shows the inner ply I2 and the outer ply I3 of the paper table 30, the loci I4 of the spot-welding being in zones coincident with the lengthwise lines running through the zones of the maximum amplitude of vibration, or the zones of the maximum potential sonorousness.

In Figure 5 is shown an Underwood noiseless typewriter having a top-cover 33, a part broken away at the front showing the inner ply I2 and the outer ply I; which are spot-welded at the loci I4 of the zones of the maximum amplitude of vibration of the plies, and also having a front cover 34, a part similarly broken away to show the outer ply I3 and the inner ply I2, and on which are loci I4 of the spot-welding. The topcover 33 and the front cover 34 are secured to the frame or casing 35 by screws 36.

In Figure 6, the usual metal segment 31 carries the segment rod 38 on which is mounted the type-bar 29 adapted to strike the platen 28, and the stop-ring 39, which has a central ridge 4U, backed by soft rubber 4|, the stop-ring 39 and its rubber backing 4| being secured to the segment 3'! by means of the screws 42. The stop-ring 39 embodies the sonorousness-destroying improvements in inner ply l2 and outer ply I3 spot-welded together at the loci indicated at l4. It is apparent that the type-bar 29 intercepts the stop-ring 39 before striking the platen and that the elasticity must suffice to quickly and effectively return the type-bar to its initial position, so that the elimination of sonorousness in the stop-ring 39 contributes substantially to complete elimination of sonorousness from the typewriter.

In Figures 8, 10, and 11, a platen 28 has the usual outer rubber cylinder 44, an inner softrubber cylinder 45 and an intermediate metal cylinder 43 embodying an inner cylinder I2 and an outer cylinder is spot-welded together at the loci l4 indicated in Figure 11, that is, at points selected most effectively to check the sonorous vibration of said cylinders.

In Figure 12, the side frame 46 of an Underwood standard typewriter has a large opening 41 which is closed by a removable panel 48 which is formed of an inner ply I2 of sheet-metal and an outer ply l3, the two plies being spot-Welded together in a central or medial zone defined by the loci 14. The frame 46 is provided with an upper flange 49 formed to provide a recess 50 for the passage of the typewriter carriage and having a pendent side Si in which are mounted screws 52 passing through tapped holes in the removable panel 48 and securing said panel 48 in the opening 41 and fast against the perpendicular wall of the pendent side It is now clear that by utilizing my improved device for eliminating sonorousness from the sheet-metal parts of a typewriting machine, I have substantially eliminated sonorousness from the entire machine, and it is further clear that my invention is similarly meritorious and useful in eliminating sonorousness from any other utensils having sheet-metal parts of steel or other Weldable worked metal.

Variations may be resorted to within the scope of the invention, and portions of the improvements may be used without others.

Having thus described my invention, I claim:

1. A typewriter provided with a keyboard and having metal types which produce noisy concussions at the operation of the keys, and having other noisy concussive metal parts, said typewriter having a framework which is muted by means of an extensive fixed frame-member that is built up of similar free-edge sheet-metal laminations whose bodies are spot-welded together at a plurality of spots in a manner to mute said machine by absorbing noise caused by the operative concussions.

2. A typewriter provided with a keyboard and having metal types which produce noisy concussions at the operation of the keys, and having other noisy concussive metal parts, said typewriter having a framework which is muted by means of an extensive fixed frame-member that is built up of similar free-edge sheet-metal laminations whose bodies are spot-welded together at a plurality of spots in a manner to mute said machine by absorbing noise caused by the operative concussions, said laminations having edgeportions that extend beyond the region of welding spots, and are free for independent vibration to effect the muting.

3. A typewriter provided with a keyboard and having metal types which produce noisy concussions at the operation of the keys, and having other noisy concussive metal parts, said typewriter having a framework which is muted by means of an extensive fixed frame-member that is built up of similar free-edge sheet-metal laminations whose bodies are spot-welded together at a plurality of spots in a manner tomute said machine by absorbing noise caused by the operative concussions, said laminations having edgeportions that extend beyond the region of welding spots, and are free for independent vibration to effect the muting, said laminations forming a panel used for enclosing noisy typewriter-mechanism, the laminations of the panel having similar contours.

4. A typewriting machine having a platen and provided with a muting device in the form of a framework-boxing to serve as a mount for the reciprocating and other concussive parts of the typewriter, said framework including an extensive area of laminated sheet-metal casing, the laminations being spot-Welded together at scattered points to give to said framework the muting capacity.

5. A typewriting machine having a platen and provided with a muting device in the form of a framework-boxing to serve as a mount for the reciprocating and other concussive parts of the typewriter, said framework including an extensive area of laminated sheet-metal casing, the laminations being spot-welded together at scattered points to give to said framework the muting capacity, said muting laminations forming the principal portion of the top plate which is arranged at the front of the platen, and overlies the main portion of the typewriter-mechanism.

6. A typewriting machine having a platen and provided with a muting device in the form of a framework-boxing to serve as a mount for the reciprocating and other concussive parts of the typewriter, said framework including an extensive area of laminated sheet-metal casing, the laminations being spot-welded together at scattered points to give to said framework the muting capacity, said muting laminations forming the principal portion of the top plate which is arranged at the front of the platen, and overlies the main portion of the typewriter-mechanism, said typewriter including a finishing case which encloses the typewriter-mechanism, and an inner framework on which said mechanism is mounted, said finishing case having side walls, a front wall, and a rear wall, said walls being formed of laminations spot-welded together at scattered points to enable them to mute the noise of the operation of the typewriter-mechanism.

WILLIAM F. HELMOND. 

